Field of the Invention
The present invention relates to a technique for composing images.
Description of the Related Art
Conventionally, a technique for multiplexing additional information of a large capacity such as audio information in a printed material such that it is difficult to distinguish visually has been disclosed (Japanese Patent Laid-Open No. 2003-174556). In recent years, it is becoming possible to obtain additional information of a large capacity that is multiplexed in a printed material by analyzing a composite image after capturing a printed material a plurality of times at a short range while moving a mobile terminal, and composing the plurality of captured images thus obtained.
In this way, a technique for composing a plurality of captured images upon a panorama capturing, for example, has been proposed as an image composing technique for composing a plurality of images (Japanese Patent Laid-Open No. 9-322059).
However, in conventional image composing techniques, a phenomenon of degradation of a captured image due to other objects such as a light source, or the like, being reflected in the printed material in a case where a printed material is captured by a camera is not considered at all.
In the case of capturing with a non-contact device such as a camera, a capturing target is mainly scenery, people, or the like, and it is uncommon that a printed material is the target. Even when a printed material is made to be a target, a continuity evaluation considering what is reflected in the printed material has not been performed. Also, there are cases where a plurality of printed materials are captured by a contact device such as a scanner, and a continuity evaluation is performed on the plurality of captured images. However, because a reflection phenomenon does not occur in capturing on a contact device, a continuity evaluation considering reflection is not performed. In other words, the phenomenon of reflection in a printed material is a completely new problem in image continuity evaluation techniques.
Specifically, there are cases in which if a plurality of printed materials are captured, and a plurality of images thus obtained are composed, a precision of an image composition degrades, or an image composition cannot be performed due to an influence of reflection.
In other words, if a printed material is captured by a camera, the content of the printed material itself cannot be distinguished due to a reflection of a light source, or the like, and the captured image is very degraded. In particular, a sheet having a high glossiness is often used for a high image quality print of a photograph, an album, or the like, but while on one side the appearance of the glossiness is very good, degradation of a captured image due to reflection is large.
In an image composing technique, processing for detecting an overlapping area at which the same/a similar object exists overlappingly in a plurality of images is important. This is, in other words, processing for searching for similar feature amounts among two images. This is a method of detecting the feature amounts of the images by using edge information of the images, for example.
FIG. 23A is an image in which an overlapping area exists in two images. Because the same “person A” exists in two images, it is possible to extract similar feature amounts for “person A”.
FIG. 23B illustrates a condition in which a reflection of another object occurs at a portion of an overlapping area “person A” in one of two images in which an overlapping area exists. Originally, the “person A” portion is an area at which edges exist and feature amounts would have been extracted, but because “person A” becomes difficult to recognize due to the reflection, the feature amounts cannot be correctly extracted. Specifically, using conventional methods, due to a reflection included in at least one of a composition target image group, similar feature amounts cannot be extracted from an overlapping area of the images, and this becomes the cause of a reduction in the precision of the image composition. Furthermore, in FIG. 23B, because a common reflection is occurring, composition processing that is not intended by a user is performed if a composition is executed by taking a reflection portion to be an overlapping area.
Accordingly, there are cases in which reflection of another object in the printed material is the cause of degradation of a captured image, and degradation of the precision of the image composition occurs, or the image composition cannot be performed with conventional image compositing techniques that do not consider reflection. Also, because image composition cannot be performed, this leads to not being able to obtain additional information of a large capacity from a printed material.